Migrate from winapi to windows-sys (#4346)

* Migrate from `winapi` to `windows-sys`

I believe that Microsoft itself is supporting the development of
`windows-sys` and it's also used by `cap-std` now so this switches
Wasmtime's dependencies on Windows APIs from the `winapi` crate to the
`windows-sys` crate. We still have `winapi` in our dependency graph but
that may get phased out over time.

* Make windows-sys a target-specific dependency

crates/runtime/src/instance/allocator/pooling/windows.rs

@@ -1,6 +1,5 @@
 use anyhow::{bail, Result};
-use winapi::um::memoryapi::{VirtualAlloc, VirtualFree};
-use winapi::um::winnt::{MEM_COMMIT, MEM_DECOMMIT, PAGE_READWRITE};
+use windows_sys::Win32::System::Memory::*;
 
 pub fn commit(addr: *mut u8, len: usize) -> Result<()> {
     if len == 0 {